besides, following on Shawn's post, Satann didn't merely lied or induced others to sin. he sinned against the holy spirit in the way he talked about Jehovah and attributing him bad things ("...He doesn't want you to know what is good...")
Besides, if Adam and Eve didn't eat the fruit and lived an happy life afterwards what would be the need to try other things? After all Jehovah is the creator, a perfect father!
For example, if a married woman has a loving husband and their relationship is perfect what would be the need to conjure... "Maybe my neighbour would be a better husband..."- That wouldn't make any sence
Also, If Satan would be allowed nonetheless to try his government, then another angel could raise up and say, no, he was bad but I can be better... and so on... That would be just ridiculous!
No, Satan was allowed to continue living only because A&E sinned
So, If there was already a civilization living happily in Jehvah's rule, all the angels would be a witness to that and no one would need to think if Jehovah is a good ruler or not. If the other civilization had sinned also, Jeovah would pause is purpose and not create A&E here while the discussion was ongoing
Think on the study classe illustration. if the teacher was already known to be giving classes to other students with 100% sucess, when the rebel student says he is not a great teacher, nno one in the classroom will believe that or have any doubts. the rebel student can be thrown out without the need to the teacher to give him the board
Clearly, if we believe in the bible and Jehovah's appointed FDS, we cannot believe there are other intelligent beings elsewhere in the Universe
Note: I believe the bible is not against the existence of other minor forms of life. While building our home during the 5 "days" he could have been doing the same on other places in the universe, since I believe in the future we can inhabit the entirety of the Universe